With respect to color photographic light-sensitive materials, the yellow, magenta and cyan dyes formed by couplers do not always possess an ideal light-absorption characteristic. For example, the magenta dye image usually absorbs some blue light in addition to the desired absorption of green light, which hampers exact color reproduction. To eliminate this hamper to color reproduction, a coupler is used which has yellow- or magenta-color before the coupling with the oxidation product of an aromatic primary amine color developing agent. The former is the so-called colored magenta coupler, and the latter is the so-called colored cyan coupler.
For the auto-masking method using such a colored coupler, detailed description appears in, for example, J. Phot. Soc. Am., 13, 94 (1947), J. Opt. Soc. Am., 40, 166 (1950) and J. Am. Chem. Soc., 72, 1533 (1950).
Colored magenta couplers showing main absorption in the blue light band are described in U.S. Pat. Nos. 2,428,054 and 2,449,966 for 1-phenyl-3-acylamino-4-phenylazo-5-pyrazolone, U.S. Pat. No. 2,763,552 for a colored magenta coupler having a 4-methoxyallylazo group, U.S. Pat. No. 2,983,608 for 1-phenyl-3-anilino-4-phenylazo-5-pyrazolone, U.S. Pat. Nos. 3,519,429 and 3,615,506 for those having a naphthylazo group, U.S. Pat. No. 1,044,778 for a colored magenta coupler having a water-soluble group, U.S. Pat. No. 3,476,564 and Japanese Patent Publication Open to Public Inspection (hereinafter referred to as Japanese Patent O.P.I. Publication) Nos. 123625/1974, 131448/1974 and 52532/1979 for those having a hydroxyphenylazo group, Japanese Patent O.P.I. Publication No. 42121/1977 for a colored magenta coupler having an acylaminophenylazo group, Japanese Patent O.P.I. Publication No. 102723/1977 for a colored magenta coupler having a substituted alkoxyphenylazo group and Japanese Patent O.P.I. Publication No. 63016/1978 for a colored magenta coupler having a thiophenylazo group.
However, none of these colored magenta couplers are satisfactory because some of them must be added in large amounts due to their low molar absorption coefficient, some of them are difficult to prepare to obtain a main absorption in the desired band, some of them have an insufficient masking effect due to their low developing activity, some of them are apt to cause fogging though their developing activity is high, some of them are low in stability to light, heat or humidity, some of them forms a magenta dye of short wavelength by reaction with the color developing agent. Therefore, it is the common practice to use them in combination of several kinds to obtain the desired performance. In recent years, there have been increasing demands for improved performance of colored magenta couplers with the use of high speed fine grain silver halide emulsions and magenta couplers with high color formation efficiency.